At present, wires and tapes based on superconducting oxides for transporting high currents are made by techniques based on shaping these materials in powder form: silkscreen printing, extrusion within a metal sheath, etc. . . . .
So far, these methods have not been able to reach desired current densities Jc, i.e. Jc (77K).apprxeq.10.sup.4 A/cm.sup.2 under zero field. The best of known results are a few 10.sup.3 A/cm.sup.2, generally accompanied by considerable degradation under a magnetic field. Thus, for high temperature superconducting oxides of the Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O types, the values of Jc are very far from the intrinsic values of Jc (77K).apprxeq.10.sup.6 A/cm.sup.2 with low sensitivity to magnetic fields as measured on oriented thin films or on monocrystals.
The article "Laser Heated Pedestal Growth of High Tc Bi-Sr-Ca-Cu-O Superconducting Fibers" by D. Gazit and R. S. Feigelson, published in the Journal of Crystal Growth 91 (1988) 318-330, proposes manufacturing a fiber of superconducting oxide having a diameter of 0.1 mm to 1 mm by growth from an extremely fine melt zone. However, such a fiber is very difficult to make.
The same implementation problems arise for structures based on fibers of Cu.sub.2 O embedded in an oriented matrix of La.sub.2-x Sr.sub.x CuO.sub.4 superconducting material as described in the article "Growth and anisotropic magnetic behavior of aligned eutectic type structures in the system La.sub.2-x Sr.sub.x CuO.sub.4 --Copper oxide" by L. Trouilleux, G. Dhalenne, and A. Revcolevschi--published in the Journal of Crystal Growth 91 (1988) 268-273.
The object of the present invention is to make tapes based on superconducting oxide which are easier to manufacture than wires or fibers known heretofore, and make it possible to achieve high current densities.